A micro-electro-mechanical device, wherein a platform is formed in a top substrate and is configured to turn through a rotation angle. The platform has a slit and faces a cavity. A plurality of integrated photodetectors is formed in a bottom substrate so as to detect the light through the slit and generate signals correlated to the light through the slit. The area of the slit varies with the rotation angle of the platform and causes diffraction, more or less marked as a function of the angle. The difference between the signals of two photodetectors arranged at different positions with respect to the slit yields the angle.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A micro-electro-mechanical device, comprising: a carrying structure; a platform coupled to the carrying structure and configured to rotate by a rotation angle (θ) with respect to the carrying structure; a physical slit opening in the platform; a support structure supporting the platform and including a cavity facing a first side of the platform; and a plurality of integrated photodetectors facing the cavity and the first side of the platform and configured to receive light beams that pass through the physical slit opening in the platform, wherein the micro-electro-mechanical device is configured to provide to a processing unit readings of the plurality of integrated photodetectors.
2. The device according to claim 1 , wherein a first photodetector of the plurality of integrated photodetectors is arranged at a first distance from the physical slit opening to generate a first light-intensity signal at a first rotation angle and a second light-intensity signal at a second rotation angle, and a second photodetector of the plurality of integrated photodetectors is arranged at a second distance from the physical slit opening to generate a third light-intensity signal at the first rotation angle and a fourth light-intensity signal at the second rotation angle.
3. The device according to claim 2 , wherein the physical slit opening has a center, and the first photodetector and the second photodetector are arranged adjacent to a bottom wall of the cavity facing the platform, the first and second photodetectors being arranged at different distances from a center line passing through the center of the slit and transverse to the bottom wall.
4. The device according to claim 3 , wherein the first photodetector is arranged along the center line, and the second photodetector is spaced apart from the center line.
5. The device according to claim 2 , further comprising the processing unit and the processing unit is configured to receive the first and third light-intensity signals from the first photodetector and the second photodetector, respectively, the processing unit includes a subtractor configured to generate a difference signal between the first light-intensity signal and the third light-intensity signal and a computing unit configured to calculate the rotation angle of the platform based on the difference signal.
7. The device according to claim 1 , wherein the plurality of photodetectors include an array of photodetectors arranged in a configuration selected from a straight line, a quadrangle, a circle, a polygon, an oval, an annular shape, and an annular sector.
8. The device according to claim 1 , wherein: the support structure includes a first substrate and a second substrate bonded together; the first substrate has a top surface facing the second substrate and forms a bottom wall of the cavity; the plurality of photodetectors are integrated in or on the first substrate; and at least one of the first substrate and the second substrate includes carrying walls that laterally delimit the cavity and include a semiconductor material.
9. The device according to claim 8 , comprising an anti-reflecting structure within the cavity and on the bottom wall or on the carrying walls.
10. The device according to claim 1 , wherein the platform includes a center, along the rotation axis, and the physical slit opening is arranged at the center of the platform.
11. The device according to claim 1 , further comprising a micromirror that includes a reflective surface on the platform.
12. The device according to claim 1 , where the support structure includes carrying walls laterally delimiting the cavity, the carrying walls including a semiconductor material.
13. A picoprojector, comprising: a micro-electro-mechanical device that includes: a platform configured to rotate by a rotation angle (θ); a physical slit opening in the platform; a support structure supporting the platform and including a cavity facing a first side of the platform; and a plurality of integrated photodetectors on the support structure and facing the cavity and the first side of the platform, and configured to generate light-intensity signals; a light source facing a second side of the platform and configured to generate a light beam, the second side of the platform being opposite to the first side of the platform; and a processing unit configured to receive the light-intensity signals from the plurality of photodetectors and calculate the rotation angle of the platform based on the light-intensity signals.
14. The picoprojector according to claim 13 , wherein: the physical slit opening has a center; the plurality of photodetectors includes a first photodetector and a second photodetector arranged at a first surface of the cavity, facing the platform, the first and second photodetectors being arranged at different distances from a center line of the physical slit opening and being configured to generate a first light-intensity signal and a second light-intensity signal, respectively; and the processing unit is configured to receive the first and second light-intensity signals and generate a difference signal from the first and second light-intensity signals and calculate the rotation angle of the platform based on the difference signal.
16. The picoprojector according to claim 13 , wherein: the support structure includes a first substrate and a second substrate bonded together; the first substrate has a top surface facing the second substrate and forms a bottom wall of the cavity; the plurality of photodetectors are integrated in or on the first substrate; and at least one of the first substrate and the second substrate includes carrying walls laterally delimiting the cavity and including semiconductor material.
17. The picoprojector according to claim 13 , wherein the micro-electro-mechanical device includes a micromirror that includes a reflective surface on the platform.
18. A method, comprising: detecting rotation of a rotatable platform of a micro-electro-mechanical device that includes a platform configured to rotate by a rotation angle (θ), a physical slit opening in the platform, a support structure supporting the platform and including a cavity facing a first side of the platform, and a plurality of integrated photodetectors facing the cavity and the first side of the platform, the detecting including: sending a light beam onto a second side of the platform, the second side being opposite to the first side of the platform; detecting, by the photodetectors, a portion of the light beam passing through the physical slit opening in the platform; producing, by the photodetectors, electrical signals correlated to a light intensity of the portion of the light beam detected by the photodetectors; and calculating the rotation angle of the platform by processing the electrical signals.
19. The method according to claim 18 , wherein: the photodetectors include first and second photodetectors; producing the electrical signals includes the first photodetector producing a first light-intensity signal and the second photodetector producing a second light-intensity signal; and processing the electrical signals includes generating a difference signal from the first and second light-intensity signals and calculating the rotation angle of the platform based on the difference signal.
21. The method according to claim 18 , comprising sending a plurality of setting light beams onto the second side of the platform, each setting light beam being sent at a different respective rotation angle of the platform; detecting, by the photodetectors, portions of the setting light beams passing through the physical slit opening; generating a plurality of sets of electrical signals by the photodetectors, each set of electrical signals being associated with a different known rotation angle of the platform and each set of electrical signals including at least three electrical setting signals generated by respective photodetectors that are aligned with each other and at different distances from the platform; calculating linearity indices as squares of amplitude differences of the electrical setting signals; and selecting a pair of photodetectors supplying maximum linearity indices as a first measure photodetector and second measurement photodetector that are used for subsequent detection of unknown rotation angles.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
September 13, 2018
July 28, 2020
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.